CN104674667B - Asymmetric triangle frame main beam concrete realizes the construction technology of continuous placing - Google Patents

Abstract

The invention discloses a kind of asymmetric triangle frame main beam concrete and realize the construction technology of continuous placing.This technique utilizes symmetric triangular rigid frame dexterously, calculate asymmetric triangle frame battered leg effect of contraction rapidly and accurately by " secondary is torn secondary open and closed " and affect coefficient, it is then determined that girder prestressing force ultra stretching amount, on the premise of allowing control stress for prestressing less than prestressed strand, realized the continuous placing of asymmetric triangle frame main beam concrete by ultra stretching technique.The present invention considers the effect of contraction of battered leg when stretch-draw girder prestressing force, therefore, can be substantially reduced construction safety risk；It addition, the continuous placing of girder can the reduction of erection time, reduce put into；Be additionally, since do not exist construction joint be also beneficial to increase triangle frame globality.Wherein, the Quantitative Calculation Method of the triangle frame battered leg effect of contraction of inventor's original creation is simple, accurately, efficiently.

Description

Asymmetric triangle frame main beam concrete realizes the construction technology of continuous placing

Technical field

The invention belongs to bridge structure field, relate to triangle frame construction technology, a kind of asymmetric triangle frame Main beam concrete realizes the construction technology of continuous placing.

Background technology

It is known that be most stable of in all nature figure intermediate cam shapes, this characteristic by numerous engineers profit With, it may be said that engineering intermediate cam shape structure is ubiquitous, in structure as firm in V leg (V leg is triangle with girder), band end bay Hold formula arch bridge (cancelling spandrel column, main, limit arch rib and girder are triangle), part beam-arch composition bridge etc..But, triangle There is a common problem in structure in engineer applied, it is simply that after triangle rock-steady structure is formed, to girder Shi Hanzhang Time, due to the effect of contraction of battered leg, prestressing force can not be effectively applied on girder.It is apparent from by structural mechanics, if ignoring axis Deformation, then prestressing force can all be applied on girder, and on battered leg internal force without impact.But practical structures the most axially becomes Shape is non-negligible, and therefore, when girder stretch-draw prestressing force, battered leg will produce " constraint " effect, offsets a part of load, Prestressing force can not be effectively applied on girder.In work progress, typically being poured by girder segmentation, prestressing force segmentation is opened Draw, then solve by the way of extension device spreading.But, girder section construction on the one hand due in work progress both sides oblique Leg is greatly increased by force unbalance, construction safety risk；On the other hand, increasing construction procedure, claim for eot, cost increases；This Outward, form construction joint, make triangle frame globality relatively be deteriorated.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of asymmetric triangle frame main beam concrete and realizes continuous placing Construction technology, this technique considers the effect of contraction of battered leg when stretch-draw girder prestressing force, calculates simple, accurately, efficiently, can be big Reduce greatly construction safety risk, time-consuming, reduce and put into.

For solving above-mentioned technical problem, the present invention by the following technical solutions: asymmetric triangle frame main beam concrete is real The construction technology of existing continuous placing, utilizes symmetric triangular rigid frame, and it is non-right to be calculated rapidly and accurately by " secondary is torn secondary open and closed " Triangle frame battered leg effect of contraction is claimed to affect coefficient, it is then determined that girder prestressing force ultra stretching amount, less than prestressed strand On the premise of allowing control stress for prestressing, realize watering continuously of asymmetric triangle frame main beam concrete by ultra stretching technique Building, wherein ultra stretching amount ε and battered leg effect of contraction affect the relational expression of coefficient e and are:

" secondary tear open secondary close " determines that battered leg effect of contraction affects the operation of coefficient e and follows the steps below:

The first step, " tearing open " asymmetric triangle frame is two symmetric figures, i, j, l of girder_bKeeping constant, one of them is right Triangle frame battered leg is claimed all to use k₁i、m₁j、l_a1And be α with horizontal line angle, numbered the most individual, another triangle frame is oblique Leg all uses k₂i、m₂j、l_a2And be β with horizontal line angle, numbered the most individual；

Second step, according to standing balance and displacement coordination equation, utilizes structural symmetry, calculates the most individual triangle frame master The actual pressure experienced of beam $F_{\mathrm{Nb}1}=\frac{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}}{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}+3k_{1}i{m}_1}F,$ Girder and battered leg intersection point horizontal displacement $u=\frac{F_{\mathrm{Nb}1}}{2j};$ The most individual actual pressure experienced of triangle frame girder $F_{\mathrm{Nb}2}=\frac{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}}{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{\text{2}}i{\cos }^2\mathrm{\β}+3k_{2}i{m}_2}F,$ Girder with Battered leg intersection point horizontal displacement

3rd step, calculates the horizontal thrust stiffness of battered leg, the most individual horizontal thrust stiffness of triangle frame battered leg The most individual horizontal thrust stiffness of triangle frame battered leg

4th step, then two symmetric triangular rigid frames " are closed " and be former asymmetric triangle frame, according to both sides battered leg level Thrust stiffness ratio determines horizontal displacement ratio, if battered leg 1 and girder intersection point horizontal displacement are x, and battered leg 2 and girder intersection point horizontal displacement For y, then x/y=t/s；Shift invariant point when finding out the i.e. girder generation compression of girder center of compression according to Displacement Ratio, false Determining battered leg 1 with girder intersection point is a away from center of compression distance, thenBattered leg 2 and girder intersection point are away from pressure Contracting centre distance $b=\frac{y}{x+y}{l}_b=\frac{1}{t/s+1}{l}_b;$

5th step, then " tearing open " be two symmetric figure triangle frames, now the most individual triangle frame only changes length as 2a into, its He keeps constant；The most individual triangle frame changes length as 2b into, and other are constant；According to above calculating, obtain now respectively The most individual actual pressure experienced of triangle frame girder $F_{\mathrm{Nb}3}=\frac{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}}{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}+3k_{1}i{m}_1(2a/l_b)}F,$ 2. The individual actual pressure experienced of triangle frame girder $F_{\mathrm{Nb}4}=\frac{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}}{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{\text{2}}i{\cos }^2\mathrm{\β}+3k_{2}i{m}_2(2b/l_b)}F;$

6th step, then two above symmetric figure triangle frame " is closed " and be former asymmetrical triangle frame, then when this When structure girder is by power F in opposite direction equal in magnitude, physical presence pressure in girderThus obtain This asymmetric triangle frame battered leg effect of contraction affects coefficient

When with ultra stretching amount ε stretch-draw girder prestress wire, check two battered leg roots the most respectively and cut Face lower edge tensile stress sigma_a1、σ_a2Need to be in permissible value:

${\mathrm{\σ}}_{a1}=\frac{(F-F_{\mathrm{Nb}})l_{a1}\sin \mathrm{\α}}{w_{z1}}\≤\left[{\mathrm{\σ}}_{a1}\right]$

${\mathrm{\σ}}_{a2}=\frac{(F-F_{\mathrm{Nb}})l_{a2}\sin \mathrm{\β}}{w_{z2}}\≤\left[{\mathrm{\σ}}_{a2}\right]$

In formula, w_z1、w_z2It is respectively battered leg module of anti-bending section (m 1., 2.³)；[σ_a1]、[σ_a2] it is respectively battered leg 1., 2. The tension limit value occurred can be allowed under current state.

The problem existed for current asymmetric triangle frame main beam concrete pouring construction, inventor is by ultra stretching Technique considers the partial prestressing load offset because of battered leg effect of contraction, reaches the purpose of main beam concrete continuous placing, Thus establish a kind of asymmetric triangle frame main beam concrete and realize the construction technology of continuous placing.This technique utilizes dexterously Symmetric triangular rigid frame, calculating asymmetric triangle frame battered leg effect of contraction rapidly and accurately by " secondary is torn secondary open and closed " affects Coefficient is it is then determined that girder prestressing force ultra stretching amount, on the premise of allowing control stress for prestressing less than prestressed strand, logical Cross ultra stretching technique and realize the continuous placing of asymmetric triangle frame main beam concrete.The present invention examines when stretch-draw girder prestressing force Consider the effect of contraction of battered leg, therefore, construction safety risk can be substantially reduced；It addition, the continuous placing of girder can the reduction of erection time, subtract Few input；Be additionally, since do not exist construction joint be also beneficial to increase triangle frame globality.

The present invention's it is crucial that the effect of contraction of quantum chemical method triangle frame battered leg, to this end, inventors herein propose asymmetric The Quantitative Calculation Method of triangle frame battered leg effect of contraction.Compared with calculating with force method or displacement method, this method calculates simple, it is not necessary to Complicated judgement and processing procedure, clear thinking, simple and clear；Further, result of calculation is accurate, can meet wanting of engineering precision Ask；Additionally, computational efficiency is high, the analyzing and processing time can be greatly saved, be more easy to be grasped by engineers, to triangle frame construction with Design has directive significance.

Accompanying drawing explanation

Fig. 1 is the calculation flow chart that in construction technology of the present invention, asymmetric triangle frame battered leg effect of contraction affects coefficient.

Fig. 2 is the asymmetric triangle frame model calculating that in the application present invention, battered leg effect of contraction affects coefficient calculation method Sketch, in figure: i, j, l_bIt is respectively the unit length bending rigidity (kN/m of girder²), unit length Anti-pull-press rigidity (kN/m), Girder length (m)；k₁i、m₁j、l_a1It is respectively battered leg unit length bending rigidity (kN/m 1.²), unit length Anti-pull-press rigidity (kN/m), battered leg 1. length (m)；k₂i、m₂j、l_a2It is respectively battered leg unit length bending rigidity (kN/m 2.²), unit length Anti-pull-press rigidity (kN/m), battered leg 2. length (m)；α, β be respectively battered leg 1., 2. with horizontal line angle (°)；F is pre-applied force (kN), F_NbFor the prestressing force (kN) being actually applied on girder.

Fig. 3 is two that in the application present invention, battered leg effect of contraction affect in coefficient calculation method that first time " tearing open " builds afterwards Symmetric triangular firm frame computing model, in figure: a be the most individual symmetric triangular rigid frame, b be the most individual symmetric triangular rigid frame；1. u is Individual symmetric triangular rigid frame battered leg and girder intersection point horizontal displacement (m)；V is the most individual symmetric triangular rigid frame battered leg and girder intersection point water Prosposition moves (m)；Other parameter tags are identical with Fig. 2.

Fig. 4 is that in the application present invention, battered leg effect of contraction affects first time " conjunction " the most asymmetric triangle in coefficient calculation method Firm frame computing model sketch, in figure: s, t are respectively battered leg horizontal thrust stiffness (kN/m) 1., 2.；X, y are respectively in external force F Under effect, battered leg 1., 2. with the horizontal displacement (m) of girder intersection point；A, b are respectively center of compression and 1., 2. with girder hand over away from battered leg The distance (m) of point；Other parameter tags are identical with Fig. 2.

In Fig. 5 application present invention battered leg effect of contraction affect in coefficient calculation method two that second time " tearing open " builds afterwards right Claim triangle frame computation model sketch, in figure: a be the most individual symmetric triangular rigid frame, b be the most individual symmetric triangular rigid frame.

In Fig. 6 application present invention, to affect in coefficient calculation method second time " conjunction " the most asymmetric triangle firm for battered leg effect of contraction Frame computation model sketch (identical with Fig. 2).

In Fig. 7 application present invention, battered leg effect of contraction affects the symmetric triangular rigid frame battered leg effect of contraction of coefficient calculation method Calculation diagram, in figure: F_NaBattered leg axle power (kN)；F_QaBattered leg shearing (kN)；F_NbGirder axle power (kN)；F_QbGirder is cut Power (kN)；F external force (kN)；E_bGirder elastic modelling quantity (kN/m²)；I_bGirder section the moment of inertia (m⁴)；A_bGirder section Area (m²)；l_bGirder length (m)；θ battered leg and horizontal line angle (°).

Detailed description of the invention

At present, concrete triangle frame construction common practice is the disposable continuous placing of main beam concrete, but when stable After triangle frame is formed, during to girder Shi Hanzhang, owing to battered leg effect of contraction can offset a part of load so that prestressing force Can not effectively be applied on girder, cause actually active prestressing force in girder can not reach to design requirement.Therefore, some work order Position takes girder segmentation to pour in construction, and then prestressing force subsection tension is avoided by the construction technology of connector spreading The adverse effect of battered leg effect of contraction.But, girder section construction also brings series of problems, on the one hand due in work progress Both sides battered leg is greatly increased by force unbalance, construction safety risk；On the other hand increasing construction procedure, claim for eot, cost increases Add；In addition form construction joint, make triangle frame globality relatively be deteriorated.

To this end, inventor establishes a kind of asymmetric triangle frame main beam concrete reality taking into full account battered leg effect of contraction The construction technology of existing continuous placing, i.e. utilizes symmetric triangular rigid frame, calculates non-rapidly and accurately by " secondary is torn secondary open and closed " Symmetric triangular rigid frame battered leg effect of contraction affects coefficient, it is then determined that girder prestressing force ultra stretching amount, less than prestress steel On the premise of bundle allows control stress for prestressing, realize watering continuously of asymmetric triangle frame main beam concrete by ultra stretching technique Building, wherein ultra stretching amount ε and battered leg effect of contraction affect the relational expression of coefficient e and are:

Wherein, " secondary tear open secondary close " determine battered leg effect of contraction affect the operation of coefficient e follow the steps below (as Fig. 1 is to shown in 7):

The first step, as shown in Figures 2 and 3, according to the difference of both sides battered leg characteristic, " tears open " to be calculated asymmetric for the first time Triangle frame is two symmetrical triangle frames, i, j, l of girder_bKeeping constant, one of them symmetric triangular rigid frame battered leg is equal Use k₁i、m₁j、l_a1And be α with horizontal line angle, numbered the most individual, another triangle frame battered leg all uses k₂i、m₂j、 l_a2And be β with horizontal line angle, numbered the most individual；

Second step, according to standing balance and displacement coordination equation, utilizes structural symmetry, calculates the most individual triangle frame master The actual pressure experienced of beam $F_{\mathrm{Nb}1}=\frac{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}}{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}+3k_{1}i{m}_1}F$ (formula (1)), girder and battered leg intersection point horizontal displacement(formula (3))；The most individual actual pressure experienced of triangle frame girder $F_{\mathrm{Nb}2}=\frac{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}}{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{\text{2}}i{\cos }^2\mathrm{\β}+3k_{2}i{m}_2}F$ (formula (2)), girder and battered leg intersection point horizontal displacement $v=\frac{F_{\mathrm{Nb}2}}{2j}$ (formula (4))；

3rd step, calculates the horizontal thrust stiffness of battered leg, the most individual horizontal thrust stiffness of triangle frame battered leg (formula (5))；The most individual horizontal thrust stiffness of triangle frame battered leg(formula (6))；

4th step, as shown in Figure 4, then by two symmetric triangular rigid frames " conjunction " for the first time and be former asymmetric triangle frame, Determine horizontal displacement ratio according to both sides battered leg horizontal thrust stiffness ratio, if battered leg 1 and girder intersection point horizontal displacement are x, battered leg 2 with Girder intersection point horizontal displacement is y, then x/y=t/s (formula (7)), the horizontal thrust stiffness of both sides battered leg liken than with horizontal displacement to Inversely prroportional relationship；Shift invariant point when finding out the i.e. girder generation compression of girder center of compression according to Displacement Ratio, it is assumed that battered leg 1 It is a with girder intersection point away from center of compression distance, then(formula (8)), battered leg 2 and girder intersection point are away from pressure Contracting centre distance $b=\frac{y}{x+y}{l}_b=\frac{1}{t/s+1}{l}_b$ (formula (9))；

5th step, as it is shown in figure 5, second time " tearing open " is two symmetric figure triangle frames, now the most individual triangle frames again Only length being changed into 2a, other holdings are constant；The most individual triangle frame changes length as 2b into, and other are constant；According to above meter Calculate, obtain the now the most individual actual pressure experienced of triangle frame girder respectively $F_{\mathrm{Nb}3}=\frac{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}}{2m_{1}j{l}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}+3k_{1}i{m}_1(2a/l_b)}F$ (formula (10)), the most individual actual pressure experienced of triangle frame girder $F_{\mathrm{Nb}4}=\frac{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}}{2m_{2}j{l}_{a2}^2{\sin }^2\mathrm{\β}+6k_{\text{2}}i{\cos }^2\mathrm{\β}+3k_{2}i{m}_2(2b/l_b)}F$ (formula (11))；

6th step, as shown in Figure 6, then by two above symmetric figure triangle frame second time " conjunction " be former asymmetrical three Angle rigid frame, then when this structure girder is by power F in opposite direction equal in magnitude, physical presence pressure in girder(formula (12)), thus obtain this asymmetric triangle frame battered leg effect of contraction and affect coefficient (formula (13)).

When with ultra stretching amount ε stretch-draw girder prestress wire, check two battered leg roots the most respectively and cut Face lower edge tensile stress sigma_a1、σ_a2In permissible value:

${\mathrm{\σ}}_{a1}=\frac{(F-F_{\mathrm{Nb}})l_{a1}\sin \mathrm{\α}}{w_{z1}}\≤\left[{\mathrm{\σ}}_{a1}\right]$ (formula (15))

${\mathrm{\σ}}_{a2}=\frac{(F-F_{\mathrm{Nb}})l_{a2}\sin \mathrm{\β}}{w_{z2}}\≤\left[{\mathrm{\σ}}_{a2}\right]$ (formula (16))

In formula, w_z1、w_z2It is respectively battered leg module of anti-bending section (m 1., 2.³)；[σ_a1]、[σ_a2] it is respectively battered leg 1., 2. The tension limit value occurred can be allowed under current state.

For ease of understanding the present invention, below symmetric triangular rigid frame battered leg effect of contraction Computing Principle is briefly described, As it is shown in fig. 7, according to mechanical knowledge, utilize the symmetry of the firm structure of triangle, arrange following equilibrium equation and displacement coordination equation (is not examined Consider detrusion):

In equation group: F_NaBattered leg axle power (kN)；F_QaBattered leg shearing (kN)；F_NbGirder axle power (kN)；F_QbGirder Shearing (kN)；F external force (kN)；E_bGirder elastic modelling quantity (kN/m²)；I_bGirder section the moment of inertia (m⁴)；A_bGirder cuts Face area (m²)；l_bGirder length (m)；K battered leg and the ratio of girder unit length bending rigidity；M battered leg and girder list The ratio of bit length Anti-pull-press rigidity；θ battered leg and horizontal line angle (°).

When easily solving proper symmetric triangular firm structure girder both sides effect one group of power F in opposite direction equal in magnitude, actual main The axle power that beam is subject to $F_{\mathrm{Nb}}=\frac{2\mathrm{mj}{l}_a^2{\sin }^2\mathrm{\α}+6\mathrm{ki}{\cos }^2\mathrm{\α}}{2\mathrm{mj}{l}_a^2{\sin }^2\mathrm{\α}+6\mathrm{ki}{\cos }^2\mathrm{\α}+3\mathrm{kim}}F.$

Below by example, calculate the asymmetric triangle of parameter of paramount importance to the present invention according to FEM model firm Frame battered leg effect of contraction affects coefficient e and verifies." Zhangzhou City's Jiulongjiang River bridge triangle firm structure construction party is write with Yu Fanglong Case is simply analysed " asymmetric triangle frame in (Chinese Water Transportation the 3rd phase of volume 12) is engineering background, and this triangle frame is carried out letter Change, by the computational methods in finite element and the present invention, its battered leg effect of contraction coefficient e is calculated respectively, specifically calculate knot Fruit is shown in Table 1.

1 two kinds of computational methods Comparative result tables of table

Conclusion: visible, finite element is essentially identical with the inventive method result of calculation, difference 0.0076, the poorest 91.2kN, phase For bigger pre-applied force negligible.Computational methods of the present invention are accurate, can meet the requirement of engineering precision.

Claims (2)

1. an asymmetric triangle frame main beam concrete realizes the construction technology of continuous placing, it is characterised in that utilize symmetrical three Angle rigid frame, calculating asymmetric triangle frame battered leg effect of contraction rapidly and accurately by " secondary is torn secondary open and closed " affects coefficient, It is then determined that girder prestressing force ultra stretching amount, on the premise of allowing control stress for prestressing less than prestressed strand, by super Tensioning process realizes the continuous placing of asymmetric triangle frame main beam concrete, wherein ultra stretching amount ε and battered leg effect of contraction shadow The relational expression ringing coefficient e is:Described " secondary is torn secondary open and closed " determines that battered leg effect of contraction affects The operation of coefficient e follows the steps below:

The first step, " tearing open " asymmetric triangle frame is two symmetric figures, i, j, l of girder_bKeep constant, one of them symmetry three Angle rigid frame battered leg all uses k₁i、m₁j、l_a1And be α with horizontal line angle, numbered the most individual, another triangle frame battered leg is equal Use k₂i、m₂j、l_a2And be β with horizontal line angle, numbered the most individual；

Second step, according to standing balance and displacement coordination equation, utilizes structural symmetry, calculates the most individual triangle frame girder real Border pressure experienced $F_{Nb1}=\frac{2m_1{\mathrm{jl}}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}}{2m_1{\mathrm{jl}}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}+3k_1{\mathrm{im}}_1}F,$ Girder and battered leg intersection point horizontal displacement $u=\frac{F_{Nb1}}{2j};$ The The most individual actual pressure experienced of triangle frame girder $F_{Nb2}=\frac{2m_2{\mathrm{jl}}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}}{2m_2{\mathrm{jl}}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}+3k_2{\mathrm{im}}_2}F,$ Girder is with oblique Leg intersection point horizontal displacement

3rd step, calculates the horizontal thrust stiffness of battered leg, the most individual horizontal thrust stiffness of triangle frame battered leg2. The individual horizontal thrust stiffness of triangle frame battered leg

4th step, then two symmetric triangular rigid frames " are closed " and be former asymmetric triangle frame, push away according to both sides battered leg level is anti- Ratio of rigidity determines horizontal displacement ratio, if battered leg 1 and girder intersection point horizontal displacement are x, battered leg 2 and girder intersection point horizontal displacement are y, So x/y=t/s；Shift invariant point when finding out the i.e. girder generation compression of girder center of compression according to Displacement Ratio, it is assumed that tiltedly Leg 1 and girder intersection point are a away from center of compression distance, thenBattered leg 2 and girder intersection point are in compression Heart distance $b=\frac{y}{x+y}{l}_b=\frac{1}{t/s+1}{l}_b;$

5th step, then " tearing open " be two symmetric figure triangle frames, now the most individual triangle frame only changes length as 2a into, and other are protected Hold constant；The most individual triangle frame changes length as 2b into, and other are constant；According to above calculating, obtain now the most individual respectively The actual pressure experienced of triangle frame girder $F_{Nb3}=\frac{2m_1{\mathrm{jl}}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}}{2m_1{\mathrm{jl}}_{a1}^2{\sin }^2\mathrm{\α}+6k_{1}i{\cos }^2\mathrm{\α}+3k_1{\mathrm{im}}_1(2a/l_b)}F,$ The most individual 3rd The angle actual pressure experienced of rigid frame girder $F_{Nb4}=\frac{2m_2{\mathrm{jl}}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}}{2m_2{\mathrm{jl}}_{a2}^2{\sin }^2\mathrm{\β}+6k_{2}i{\cos }^2\mathrm{\β}+3k_2{\mathrm{im}}_2(2b/l_b)}F;$

6th step, then two above symmetric figure triangle frame " is closed " and be former asymmetrical triangle frame, then when this structure When girder is by power F in opposite direction equal in magnitude, physical presence pressure in girderThus it is non-to obtain this Symmetric triangular rigid frame battered leg effect of contraction affects coefficient

Construction technology the most according to claim 1, it is characterised in that when with ultra stretching amount ε stretch-draw girder prestress wire Time, two battered leg root section lower edge tensile stress sigma_a1、σ_a2Need to be in permissible value:

${\mathrm{\σ}}_{a1}=\frac{(F-F_{Nb})l_{a1}sin\mathrm{\α}}{w_{z1}}\≤\[{\mathrm{\σ}}_{a1}\]$

${\mathrm{\σ}}_{a2}=\frac{(F-F_{Nb})l_{a2}sin\mathrm{\β}}{w_{z2}}\≤\[{\mathrm{\σ}}_{a2}\]$

In formula, w_z1、w_z2It is respectively battered leg module of anti-bending section 1., 2.；[σ_a1]、[σ_a2] be respectively battered leg 1., 2. current state The tension limit value occurred can be allowed down.